refactor(llm): clarify request context immutability

packages/client/ui-conversation/src/client/chat/StatsLine.tsx

@@ -96,6 +96,8 @@ export const StatsLine = memo(function StatsLine({ useSession, useProjection }:
     const cacheHit = cacheHitPercent(usage)
     if (cacheHit !== null) parts.push(`cache hit ${cacheHit}%`)
   }
+  // contextPercent validates both fields; repeat the capacity guard so that
+  // TypeScript carries the same refinement into the formatting branch.
   parts.push(context === null || modelRequest?.contextWindow === undefined
     ? 'context unknown'
     : `context ${context}% of ${formatMetricTokens(modelRequest.contextWindow)}`)

packages/llm/llm/src/index.ts

@@ -448,7 +448,7 @@ export class LlmService extends Service {
     const resolvedConfig = deepFreeze(structuredClone(resolved.config))
     const context = resolved.context === undefined
       ? undefined
-      : Object.freeze(structuredClone(resolved.context))
+      : deepFreeze(structuredClone(resolved.context))
     let dispatched = false
     return Object.freeze({
       config: resolvedConfig,